ImmunoGen Climbs Most Since 1989 as Cancer Drug Trial Succeeds

ImmunoGen Inc. shares gained the most in 34 years after the company’s targeted therapy succeeded in a trial against a hard-to-treat form of ovarian cancer.

(Bloomberg) — ImmunoGen Inc. shares gained the most in 34 years after the company’s targeted therapy succeeded in a trial against a hard-to-treat form of ovarian cancer.

In the trial of 453 patients who had already received other therapies for the stubborn form of treatment-resistant cancer, those that received ImmunoGen’s Elahere survived significantly longer on average than those receiving other standard interventions chosen by their doctors, the company said Wednesday in a statement. The shares rose as much as 131% at the New York market open, the most since December 1989. 

ImmunoGen is among a host of companies developing antibody-drug conjugates to treat cancer — precision medicines that deliver potent tumor-killing doses that might be too toxic to use systemically. They deposit a strong concentration of drug directly at a tumor site, which may increase efficacy with fewer side effects. Pfizer Inc. agreed in March to purchase Seagen Inc., another maker of ADCs, for $43 billion to help replenish its pipeline.

Elahere is already approved for treatment of peritoneal and fallopian tube tumors. The ovarian cancer trial demonstrated its treatment’s “superiority to chemotherapy based on all efficacy endpoints, in particular overall survival,” ImmunoGen said, and it plans to submit the data later this year to regulators in the US and Europe for expansion of the drug’s clearance. The full results will be presented at a medical meeting later this year, Immunogen said. 

Immunogen said its drug cut the risk of disease progression by 35% compared to chemotherapy alone and it slashed the risk of death by 33%. BMO analyst Etzer Darout called the results “simply marvelous,” noting that Elahere is the first drug to demonstrate an overall survival benefit in this type of cancer. 

The trial tested Elahere in patients with a form of platinum-resistant ovarian cancer. About 20,000 people are diagnosed with ovarian cancer in the US each year and most undergo surgery followed by platinum drug-based chemotherapy. The majority of patients eventually develop platinum-resistant disease, which is difficult to treat, and about 13,000 ovarian cancer patients die annually. 

“We view these data as very positive, and believe this should remove any doubts that Elahere will get confirmatory approval by the FDA,” Truist Securities analyst Asthika Goonewardene said in a note to clients. 

–With assistance from Carmen Reinicke.

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